summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJim Mattson <jmattson@google.com>2021-04-21 17:18:34 -0700
committerPeter Zijlstra <peterz@infradead.org>2021-04-22 14:36:01 +0200
commit4b2f1e59229b9da319d358828cdfa4ddbc140769 (patch)
treef53b83638635ae507f58751932438200e8898a2a
parent9d480158ee86ad606d3a8baaf81e6b71acbfd7d5 (diff)
perf/x86/kvm: Fix Broadwell Xeon stepping in isolation_ucodes[]
The only stepping of Broadwell Xeon parts is stepping 1. Fix the relevant isolation_ucodes[] entry, which previously enumerated stepping 2. Although the original commit was characterized as an optimization, it is also a workaround for a correctness issue. If a PMI arrives between kvm's call to perf_guest_get_msrs() and the subsequent VM-entry, a stale value for the IA32_PEBS_ENABLE MSR may be restored at the next VM-exit. This is because, unbeknownst to kvm, PMI throttling may clear bits in the IA32_PEBS_ENABLE MSR. CPUs with "PEBS isolation" don't suffer from this issue, because perf_guest_get_msrs() doesn't report the IA32_PEBS_ENABLE value. Fixes: 9b545c04abd4f ("perf/x86/kvm: Avoid unnecessary work in guest filtering") Signed-off-by: Jim Mattson <jmattson@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Peter Shier <pshier@google.com> Acked-by: Andi Kleen <ak@linux.intel.com> Link: https://lkml.kernel.org/r/20210422001834.1748319-1-jmattson@google.com
-rw-r--r--arch/x86/events/intel/core.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 37ce38403cb8..c57ec8e27907 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4516,7 +4516,7 @@ static const struct x86_cpu_desc isolation_ucodes[] = {
INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_D, 3, 0x07000009),
INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_D, 4, 0x0f000009),
INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_D, 5, 0x0e000002),
- INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_X, 2, 0x0b000014),
+ INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_X, 1, 0x0b000014),
INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X, 3, 0x00000021),
INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X, 4, 0x00000000),
INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X, 5, 0x00000000),